1. Field of the Invention
The object of the invention is a control of an elevator group, and also a method for allocating calls in an elevator system in such a way that set objectives are fulfilled.
2. Background of the Invention
Among many other different tasks, one basic function of a control of an elevator group is the allocation of calls. The objective of allocation is to give calls to be served by the elevator cars in such a way that some performance indicator describing the system is as good as possible. Conventionally the most commonly used performance indicators relate to call times and passenger waiting times. Typically averages are calculated from these times and their distributions are determined. It can also be arranged such that different indicators are weighted in different traffic situations. This is to give the system the opportunity to adapt to the prevailing traffic situation.
The power requirement of an elevator system varies according to the loading and the control situation. For example, during acceleration the power requirement is transiently over double compared to the power required during even speed. In this case the current taken by the elevator from the supply network of the building also varies, and e.g. dimensioning of the fuses in the electricity supply of the building must be done according to the maximum supply current of the elevator. The elevator also returns some of the committed energy to the system during motor braking. This energy returned to the power supply system is conventionally converted into heat in a separate power resistor or it is returned to the supply network.